PRELIMS Flashcards
The medical imaging technique used in radiology to form pictures of the anatomy and the physiological processes of the body.
MRI
MRI scanners use strong ______ fields, magnetic field ________, and _______ waves to generate images of the organs in the body.
- strong magnetic field
- magnetic field gradients
- radiowaves
He is the inventor of the first magnetic resonance scanning machine celebrates his 85th birthday on March 16.
Dr. Raymond Damadian
He is a physician performed the first full-body scan of a human being in 1977.
Dr. Raymond Damadian
MR imaging was invented by _____ _ __________ mechanism to encode spatial information into who developed NMR signal using magnetic field gradients in September 1971; he published the theory behind it in March 1973.
Paul C. Lauterbur
Damadian built the first whole-body MRI scanner in 1977, which he called the __________ (impossible).
Indomitable
_________ was able to image a student’s finger in 15-23 minutes in 1974.
Mansfield
_______________ is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials.
magnetic field
___________ is a material or object that produces a magnetic field.
magnet
it is the small, dense region consisting of protons and neutrons at the center of an atom
atomic nucleus
In 1911, he discovered the atomic nucleus based on the 1990 Geiger-Marsden Gold Foil experiment.
Ernest Rutherford
________ is a quantum-mechanical property, akin to the angular momentum of a classical sphere rotating on its axis, except it comes in discrete units of integer or half-integer multiples of ħ.
proton spin
_______________ is a medical procedure in which part of the electrical conduction system of the heart, tumor or other dysfunctional tissue is ablated medium frequency alternating current.
radiofrequency
Radiofrequency ablation also called ___________.
fulguration
These are materials where the magnetic field is generated by the internal structure of the material itself.
permanent magnet
the uniform magnetic field is found inside the coil, especially in the center
these magnets are relatively inexpensive to make but require a large constant flow of current while magnetized and imaging
resistive magnet
a superconducting magnet is an elecromagnet made from coils of superconducting wire
most MRI systems use this magnet
superconductive magnet
is the time constant which determines the rate at which excited protons reach equilibrium or go out of phase with each other
it is a measure of the time taken for spinning protons to the coherence among the nuclei spinning perpendicular to the field
T2 or Transverse Relaxation Time
is the concentration of signal bearing spins
spin density
TR is the amount of time between successive pulse sequences applied to the same slice
repetition time
TE is the time between the delivery of the rf pulse and the receipt of echo signal
time to echo
often denoted by the symbol gamma
it is the ratio of the magnetic momentum in a particle to its angular momentum
gyromagnetic ratio
is a measure of torque exerted on a magnetic system (bar magnet or dipole) when placed in a magnetic field and that for a magnet is the product of the distance between its poles and the strength of either pole
magnetic momentum
also known as spin, is the velocity of rotation of something around an axis
angular momentum
are the simple devices that exploit the conservation of angular momentum to stabilize, guide or measure rotational movemeng in many types of systems
gyroscopes
is a special case of forced vibrations
when the frequency of an extremely applied periodic force on a body is ewual to its natural frequency, the body rapidly begins to vibrate with an increased volume
resonance
are critical to nuclear excitation and signal reception in MRI
radiofrequency fields
these frequencies are in the RF range which are much lower than xrays and do not disrupt living tissue
larmour frequency
is the summation of all the magnetic moments of the individusl hydrogen nuclei
net magnetization
Felix ____ and Edward ______ first discovered the properties of magnetic resonance
Felix Bloch and Edward Purcell
Felix Bloch and Edward Purcell used this technique for analysis of complex molecular structures and dynamic chemical processes
MRI spectroscopy
device for transmitting or receiving radiowave
antenna
spurious finding in or distortion of image
artifacts
reduction in energy or amount kf a beam of radiation when it passes through tissue or other substances
attenuation
single or multiple loops of wire designed to produce a magnetic field from the current flowing through a wave
coil
the fear of a having no escape and being in closed or small spaces of rooms
claustrophobia
relating to extremely low temperature
cryogenic
spontaneous random motion of molecules in a medium
diffusion
fat tissue in the image is made to be of a lower, darker signal intensity
fat suppressed images
signal emitted by tissue after RF excitation
free induction decay
technique used in reducing motion artifacts
gating
fast pulse sequence, often used with 3D imaging to generate T2 weighted images
gradient echo
a change in the intensity of a magnetic field in space
mT/cm
gradient magnetic field
standard pulse sequence available in modt MRI imagers
inverse recovery
a force is created when the magnetic dipole is in a magnetic field
magnetic moment
the largest dcale macroscopic magnetic moment resulting from many nuclear magnetic moment
magnetization
magnetic moments of individual hydrogen nuclei aligned in the external magnetic field
net magnetization
flow of blood through vessels of an organ or anatomic structure
perfusion
the wobble of the rotational axis of a spinning body about a spinning body about a stationary axis
precision
SI unit of magnetic field strength
1T = 10,000 G
tesla
suppresses signal from cerebospinal fluid (CSF)
fluid attenuated inversion recovery (FLAIR)
the primary visual factor, determined by RF signal strength
brightness
brighter than its surroundings
hyperintense
darker than its surroundings
hypointense
determined by the size and depth of tissue voxel
determines the smallest tissye differences that can be an image, therefore image resolution
section thickness
manipulation of extrinsic parameters controls the acquisition of various T1, T2 and PD measurements thus affectijg image quality
imaging parameters
ability to distinguish one structure from another
determined by the homogeneity of Bo, steepness of gradient fields and scan time
spatial resolution
spatial resolution of current MRI is . mm
0.1 mm
noise produced by increase random molecular motion with increase in body temperature
thermal noise
extraneous visual information
signal to noise ratio
metal with a paramagnetic effect
gadolinium
a new manganese based paramagnetic liver contrast agent
used in detection, characterizatjon, localization and evaluation of lesions in the liver
teslascan
an iron oxide mixture and the only supramagnetic contrast agentd available
used to detect and diagnose liver lesions
feridex
technique used to organize the signal, for improving image quality, to reduce motion artifacts from the beating heart
gating
uncontrolled by the operator
intrinsic
controlled by the operator
extrinsic
angle of inclination from the longitudinal axis
flip angle
artifact
increase of T2 time, bright signal in tendons
magic angle artifact
artifact
loss of contrast between two adjacent tissues
partial volume artifact
artifact
signal dropouts, bright spots and spatial distortion
metal artifact
artifact
blurring and ghosting
motion artifact
artifact
static on image
herringbone artifact
artifact
image non uniform
RF overflow/data clipping artifact
artifact
localized inhomogenous brightness
shady artifact
artifact
staircase like nuance
stair case artifact
artifact
image wrap around
aliasing artifact
artifact
bands through image center
zipper artifact
